One way to close a circuit connection is by way of an electro-mechanical relay. In its simplest form, a relay merely makes or breaks a single circuit connection (i.e., it opens or closes a path through which current may flow). Depending on the relay's intended use, a biased conductor which makes the circuit connection is biased so that the connection is “normally open” or “normally closed”. An armature which is movable between first and second positions then presses on the biased conductor when the armature is moved to one of its positions, and the pressing on the biased conductor causes the biased conductor to move from its biased state. In this manner, a normally open connection may be closed, and a normally closed connection may be opened. Movement of the armature is controlled by an electro-magnetic actuator assembly. Typically, the actuator assembly will comprise a magnetic core encircled by an electric coil. The ends of the coil are coupled to a control circuit. When the control circuit is closed, current flows through the coil and causes the magnetic core to exert an attractive or repelling force which causes a relay's armature to move out of its biased position. When the control circuit is opened, current ceases to flow through the coil and the magnetic force exerted by the core ceases to exist. Opening the control circuit therefore allows a relay's armature to return to its biased position. While the movement of an armature is typically rotational (e.g., the armature is mounted within a relay using pins which lie on the armature's rotational axis), the movement of an armature is sometimes translational (e.g., the armature is mounted so that it travels along a track).
While some simple relays comprise only a single circuit, and therefore a single current path which may be opened or closed, other relays comprise two or more circuits through which current may alternately flow, depending on which of the two or more circuits is currently closed. In some relays, two alternate circuit paths will comprise a pass-through circuit path and an attenuated circuit path. The pass-through circuit path simply allows electrical signals to flow through the relay without attenuation. On the other hand, and as its name implies, the attenuated circuit path attenuates electrical signals which flow through the relay.
With advances in manufacturing technology, electronic devices have become increasingly smaller. As a result, the size of electro-mechanical relays has decreased. However, as pass-through and attenuator circuits are mounted in closer proximity of one another, there is a greater chance that the two circuits will interfere with one another. For example, an electrical signal flowing through an attenuator circuit may receive unwanted attenuation from an open pass-through circuit or vice versa. The open circuit acts as an antenna which receives stray electrical signals and then capacitively transfers the stray signals to the closed circuit. Because this interference may increase as the distance separating the relevant circuits decreases, reducing this interference to a manageable level has become an increasingly important design criterion for miniature relays.
An example of a typical electro-mechanical relay comprising pass-through and attenuator circuits, which is hereby incorporated by reference for all that it discloses, is disclosed in the U.S. patent of Blair et al. entitled “Attenuator Relay” (U.S. Pat. No. 5,315,273). The relay disclosed by Blair et al. is intended to be housed in a cannister having a volume of approximately 0.05 cubic inches. While such a miniature relay is adequate for some applications, the close proximity of its pass-through and attenuator circuits results in too much noise in other applications.